For cards, 2 1/2 x 3 1/2"....
The first picture shows how to cut an 8.5 x 11 piece of paper into 10 pieces. You start at the arrow for the first cut. The black section shows the scraps that are left... not much waste! (Click on either picture to enlarge it.)
The next picture shows how to cut a 12 x 12 piece of paper into 16 pieces. You basically cut to the 7" mark and stop, rotating the paper to repeat the process. Then each 5 x 7 piece can be cut exactly into four 2 1/2" by 3 1/2" pieces...a total of 16 pieces, with a tiny white square in the middle left over.
This picture shows how to cut your 8 1/2 x 11 paper for a FOLDING LTC...
Your first cut should be the vertical pink line shown.
Each piece is 3.5 x 5". The pink and the black solid lines are the cut lines, while the dashed lines are the fold lines.
This is a template for cutting 12 x 12 cardstock into the maximum number of LTCs for a FOLDED LTC layout. It will yield the 4 larger 5 x 7 pieces, which are then cut once more in half. The diagram shows the folds as dashed lines, and the solid lines are the cut lines. And if you're NOT planning to fold the cards, just cut on all the lines! Hope this helps!
The last picture shows the cutting dimensions for a 22 x 28 piece of posterboard, which would make 70 LTCs.
...a 6x9 envelope may be mailed as a first class "Letter" if it is not more than 0.25 inches thick.
...if a 6x9 envelope is between 0.25 and 0.75 inches thick, it is considered a "Large Envelope."
...if it is not uniformly thick and/or exceeds 0.75 inches of thickness, it is considered a "Package."
It saves a lot of postage if you arrange your cards as flat as possible inside your envelope... don't just dump them into the mailing envelope (you'll get a bulge and an extra postal charge).
I have a piece of cereal-box cardboard cut with two slots: 0.25 inch and 0.75 inch. I can slip my envelopes through and determine if I'll get charged extra postage.
top slit, 1/4 "
bottom slit, 3/4"